Slaughterhouse - In the East Wing, grab onto a box being moved by a crane and fall into the pit it goes over. At the end of the pit is a chest with the PA 1 inside of it

Slaughterhouse - In the North Wing, upon entering a large room with two Cyclopius Unit M39s go to the left conveyor belt and crouch under a wall. After sneaking by some guards it is found inside a chest

Slaughterhouse - In the North Wing, after obtaining the second fuse, there is an Alpha Section soldier standing on a ramp. After killing him the PA 1 can be found in a chest past him

Selene - Once landed in the Transmitter Entrance, it is in a veding machine